Acrocalymma Alcorn & J.A.G. Irwin, Trans. Br. Mycol. Soc. 88(2): 163 (1987)
Facesoffungi number: FoF 07097
Index fungorum: 11008
Dothideomycetes, Pleosporomycetidae, Pleosporales, Acrocalymmaceae
Saprobic on terrestrial host plant and freshwater water habit. Sexual morph: Ascomata initially immersed, later becoming erumpent, globose, unilocular, covered with light pale grey hyphae, opening by a centrally located ostiole, with a long break. Ostiole cylindrical, filled with hyaline periphyses. Peridium composed of thick-walled, brown cells of textura angularis. Hymenium composed of numerous, hyaline, filliform, septate, anastomosed pseudoparaphyses and asci. Asci bitunicate, 8-spored, cylindrical, short pedicellate. Ascospores biseriate, initially hyaline, ultimately becoming brown or pale reddish brown, narrowly fusiform, straight or slightly curved, 1–3-septate, constricted at septa, thick-walled, guttulate, enclosed by 1–2 μm wide, hyaline sheath. Asexual morph: Conidiomata dark brown to black, solitary to gregarious or confluent, immersed to semi-immersed, stromatic, pycnidial, globose to subglobose, pyriform, unilocular or multi-locular, ostiolate. Ostiole circular, cylindrical, straight or curved, centrally or laterally located. Conidiomatal wall composed of brown to paler, thick-walled cells of textura angularis to textura globosa or textura prismatica. Conidiophores reduced to conidiogenous cells. Conidiogenous cells hyaline, enteroblastic, phialidic, ampulliform to subcylindrical or lageniform, smooth-walled. Conidia hyaline, cylindrical to fusiform, aseptate or 1–3-septate, bearing helmetshaped, mucoid appendage at each end.
Type species: Acrocalymma medicaginis Alcorn & J.A.G. Irwin, Trans. Br. Mycol. Soc. 88(2): 163 (1987)
Notes: Acrocalymma was introduced by Alcorn and Irwin (1987) for a single species, A. medicaginis, which was associated with a root and crown rot disease of Medicago sativa (Fabaceae). Acrocalymma is characterized by globose conidiomata with a long pycnidial beak, and hyaline, or becoming pale brown with age, cylindrical to fusiform, aseptate, or 1–3-septate conidia, bearing an appendage at one or both ends. Za.
Distribution: Australia, India, Spain, Thailand, USA (Alcorn and Irwin 1987; Nag Raj 1993; Trakunyingcharoen et al. 2014, this study).